Dental crown and backing.



R. E. CAMPBELL; A DENTAL CROWN AND BACKING.

Patented June 4, i912.

APPLICATION FILED JULY 20, 1911.

COLUMBIA PLANUGRAFH co., wAsHlNaToN. n, c,

ROBERT E. CAMPBELL, OF BERKELEY, CALIFORNIA.

DENTAL CROWN AND BACKING.

Specification of Letters Patent.

Application led July 20, 1911.

Patented June 4, 1912.

Serial No. 639,548.

To all whom it may concern:

Be it known that I, ROBERT E. CAMPBELL, citizen of the United States, residing at. Berkeley, in the county of Alameda and State o-f California, have invented new and useful Improvements in Dentalv Crowns and Backings, of which the following is a speciication.

This invention relates to an artificial tooth, and particularly pertains to a dental crown and a backing therefor.

It is the object of this invention to pro-- vide a backing for a dental crown which is so designed and constructed as to form a substantial and rigid support for a porcelain crown, or the like, and which is so arranged that the crown may be easily andv quickly mounted thereon.

Another object is to provide a porcelain crown and a backing therefor which are adapted to be securely connected together and readily assembled in the mouth, andi which is so arranged as to facilitate the substitution of the crown in event the latter be-` comes broken without necessitating the re? moval of the backing.

Other objects will become apparent hereinafter.

The invention consists of the parts and the construction and combination of parts as hereinafter more fully described and claimed, having reference to the accompanying drawings, in which- Figure 1 is an enlarged vertical section of; the invent-ion as applied. Fig. 2 is a det-ail perspective of the crown. Fig. 3 is a det-ail perspective of the backing. Fig. 4 is a similar view of a conical nut employed in attaching the crown to the backing. Fig. 5 is a detail in perspective of a modied form of the crown. Fig. 6 is aV detail in perspec* tive of a modified form of the bacln'ng. Fig. 7 is a section of the crown and backing assembled and showing a further modification of the invention. Fig. 8 is a rear elevation of the backing, showing same as mounted in series.

In the drawings, A represents a dental crown, preferably made of porcelain orlike material, in the form of the exposed portion of a tooth.

B is a thin metallic plate, on the face of which the crown A is to be mounted; the plate B forming a backing for the latter. The plate B is provided with a single perforation 2, and is formed with an outwardly plate.

one or more pins vor studs 5, preferably two '1n number, which are disposed on the plate B at diametrically opposite sides of the perforation 2 in close proximity thereto, `'and project outwardly a short distance substantially at right angles to the face of the These studs 5 may be arranged in vertical relation to the perforation 2, as shown in Fig. 3, or horizontally, as shown in Fig. 6, or in any other desired position, the essential feature being to provide aprojection on the plate B, adjacent the perforation 2, which is adapted to enter a recess or depression 6 formed in the back of the crown A. The recess or recesses 6 in the crown A are arranged to correspond to and register with the pin or pins 5 on t-he plate B.

The back of the crown A is provided with a single threaded stem 7, which is rigidly secured to the crown, and is so disposed thereon as to extend through the perfo-ration 2 in the plate B when the crown is placed on the latter with the pins 5 extending into the recesses 6;y the stem 7 being of such length as to extend beyond the vback of the plate B to a point substantially in alinement'with the outer end of the divergent ange 8.

A conical shaped nut 8, the tapered portion of which corresponds to and is designed to fit the tapered inner wall of the flange 3, is provided,and is adapted to be screwed on the outer end Vof the stud 7 when the latter is inserted through the perforation 2, as shown -in Fig. 1. The outer or large end of the nut 8 is provided with a square portion 9 which forms a gripping surface for tweezers or like instrument and facilitates the turning of the nut on or olf the stem 7.

In the applicationy of thevinvention, the

crown A is placed on the backing plate B with the threaded stem 7 extending through the'perforation 2 in the plate and the pins 5 on the plate projecting intothe recesses 6 inthe crown A, as shown in Fig. 1, the adjacent or contacting faces of the crown and plate being previously coated with a suitable cement. The conical nut 8 is then screwed `on the stem 7 and acts to vdraw and securely clamp the crown A against the face of the plate B. The perforation 2 is sufficiently larger than the-stem 7 to admit of a portion of the cement passing therethrough and spreading between the nut 8 and the flange 3, so as to form a tight and septic joint, and also rigidly retain the nut 8 in place and prevent its working loose.

The backing plate B is now attached to the tooth in any suitable manner, the method commonly employed being to solder it to a pin 10 previously mounted in the tooth, as shown in Fig. l, the solder indicated at l being used for this purpose; this solder being placed on the back of the plate B to the desired thickness so as to surround and practically embed the tapered flange 3.'

After the solder 4 has been applied to the required depth and sufficiently hardened, it is dressed 0E on the back and the projecting end of the nut 8, and flange 3 'is cut down so as to be flush therewith and thus form a smooth even surface.

Ihe purpose of the pins 5 which engage the crown A is to prevent the crown A being rotated when-the nut 8 is being secured in place, and also to add rigidity to the connected parts. It is obvious that the pins 5 could be formed on the crown and extend into perforations in the plate B, but such construction would be undesirable where porcelain crowns are used, for the reason that in baking porcelain crowns around metallic pins, the porcelain is weakened adjacent to the metal and is liable to crack, as has been determined by practice. In forming the perforations or recesses 6 in the porcelain, as herein shown and described, no such difculty is encountered. Thus, by mounting a single pin 7 in the crown and forming recesses therein, as before mentioned, a strong construction is obtained which could not otherwise be accomplished. The recesses 6 are comparatively small and shallow; being only of such dept-h as to insure secure engagement with the pins 5, so that the porcelain crown A will be but slightly reduced at this point and is not weakened to any serious extent.

It is apparent that in the event a crown A becomes cracked or broken and it is necessary to replace it with a new one, it may be readily removed without disturbing the backing plate B by removing the nut 9 from the stem 7; another crown being set in place on the backing plate A, as before described.

The nut 8 acting as it does to draw the porcelain crown A against the plate B, admits of the plate B being formed of thin sheet material, and insures a tight joint between the back of the crown and the face of the plate.

. It is obvious that the plate B may be mounted in any desired manner, and that a series of plates may be mounted side by side where it is necessary to mount a number of the dental crowns A adjacent to each other, as shown in Fig. 8.

Having thus described my invent-ion, what I claim and desire to secure by Letters Patent isl. A backing for a dental crown consisting of a metallic plate formed with a perforation therethrough, and having an annular flange surrounding the perforation on one side of the plate, and a projection formed on the other side ofthe plate.

2. A backing for a dental crown,'compris ing a metallic plate formed with a perforation therethrough, said plate having projections on both sides one of said projections being of tubular form and axially alined with said perforation, said tubular project-ion having outwardly diverging walls.

V3. A backing for a dental crown, comprising a metallic plate formed with a perforation therethrough2 said plate having a plurality of pins projecting from one side and having a projection of tubular form on the other side axially in line with said perforation, said pins adaptedto enter recesses in the back of the crown.

t. In a dental crown and a backing therefor, the combination of a plate formed with a perforation therethrough, said plate having projections on both sides, one of said projections being of tubular form and axially alined with the perforation, a crown having a threaded stern formed thereon, said stem adapted to extend through the perforation in the plate and through the tubular projection, and a nut to be screwed on the portion of the stem within the tubular projection to thereby bind the plate and crown together.

5. In a dental crown, and backing therefor, the combination of a plate having a perforation therethrough, said plate having projections on both sides, one of said projections being of tubular form with outwardly diverging walls and arranged axially in line with the perforation, a crown having a threaded stem adapted to extend through the perforation in the plate and through said projection, and a conical nut to be screwed on that portion of the stem.

within the tubular projection, said nut adapted to bear against the divergent walls of said projection. Y

6. In a dental crown and a backing therefor, the combination of a plate having a perforation therein, an annular divergent flange surrounding the perforation, acrown having a threaded stem mounted thereon, said stem adapted to extend through the perforation in the plate, `a conical nut to be screwed on the stem to bind the plate and crown together, said nut to bear against the divergent Walls of the flange on the plate, In testimony whereof I have hereunto and means for connecting the adjacent faces set my hand in the presence of two subof the plate and crown to prevent their scrbing Witnesses.

turning in relation to each other, said means ROBERT E. CAMPBELL. consisting of projections on the plate and Witnesses:

recesses on the crown into which the pro- R. S. BERRY,

ject-ions on the plate extend. S. N. WYoKoFF.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

' Washington, D. C. 

